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| 1 | +/* | |
| 2 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 3 | + * | |
| 4 | + * This code is free software; you can redistribute it and/or modify it | |
| 5 | + * under the terms of the GNU General Public License version 2 only, as | |
| 6 | + * published by the Free Software Foundation. Oracle designates this | |
| 7 | + * particular file as subject to the "Classpath" exception as provided | |
| 8 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 9 | + * | |
| 10 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 11 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 12 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 13 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 14 | + * accompanied this code). | |
| 15 | + * | |
| 16 | + * You should have received a copy of the GNU General Public License version | |
| 17 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 18 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 19 | + * | |
| 20 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 21 | + * or visit www.oracle.com if you need additional information or have any | |
| 22 | + * questions. | |
| 23 | + */ | |
| 24 | + | |
| 25 | +/* | |
| 26 | + * This file is available under and governed by the GNU General Public | |
| 27 | + * License version 2 only, as published by the Free Software Foundation. | |
| 28 | + * However, the following notice accompanied the original version of this | |
| 29 | + * file: | |
| 30 | + * | |
| 31 | + * Written by Doug Lea with assistance from members of JCP JSR-166 | |
| 32 | + * Expert Group and released to the public domain, as explained at | |
| 33 | + * http://creativecommons.org/publicdomain/zero/1.0/ | |
| 34 | + */ | |
| 35 | + | |
| 36 | +package java.util.concurrent; | |
| 37 | +import java.util.*; | |
| 38 | +import java.util.concurrent.atomic.AtomicInteger; | |
| 39 | +import java.security.AccessControlContext; | |
| 40 | +import java.security.AccessController; | |
| 41 | +import java.security.PrivilegedAction; | |
| 42 | +import java.security.PrivilegedExceptionAction; | |
| 43 | +import java.security.PrivilegedActionException; | |
| 44 | +import java.security.AccessControlException; | |
| 45 | +import sun.security.util.SecurityConstants; | |
| 46 | + | |
| 47 | +/** | |
| 48 | + * Factory and utility methods for {@link Executor}, {@link | |
| 49 | + * ExecutorService}, {@link ScheduledExecutorService}, {@link | |
| 50 | + * ThreadFactory}, and {@link Callable} classes defined in this | |
| 51 | + * package. This class supports the following kinds of methods: | |
| 52 | + * | |
| 53 | + * <ul> | |
| 54 | + * <li> Methods that create and return an {@link ExecutorService} | |
| 55 | + * set up with commonly useful configuration settings. | |
| 56 | + * <li> Methods that create and return a {@link ScheduledExecutorService} | |
| 57 | + * set up with commonly useful configuration settings. | |
| 58 | + * <li> Methods that create and return a "wrapped" ExecutorService, that | |
| 59 | + * disables reconfiguration by making implementation-specific methods | |
| 60 | + * inaccessible. | |
| 61 | + * <li> Methods that create and return a {@link ThreadFactory} | |
| 62 | + * that sets newly created threads to a known state. | |
| 63 | + * <li> Methods that create and return a {@link Callable} | |
| 64 | + * out of other closure-like forms, so they can be used | |
| 65 | + * in execution methods requiring <tt>Callable</tt>. | |
| 66 | + * </ul> | |
| 67 | + * | |
| 68 | + * @since 1.5 | |
| 69 | + * @author Doug Lea | |
| 70 | + */ | |
| 71 | +public class Executors { | |
| 72 | + | |
| 73 | + /** | |
| 74 | + * Creates a thread pool that reuses a fixed number of threads | |
| 75 | + * operating off a shared unbounded queue. At any point, at most | |
| 76 | + * <tt>nThreads</tt> threads will be active processing tasks. | |
| 77 | + * If additional tasks are submitted when all threads are active, | |
| 78 | + * they will wait in the queue until a thread is available. | |
| 79 | + * If any thread terminates due to a failure during execution | |
| 80 | + * prior to shutdown, a new one will take its place if needed to | |
| 81 | + * execute subsequent tasks. The threads in the pool will exist | |
| 82 | + * until it is explicitly {@link ExecutorService#shutdown shutdown}. | |
| 83 | + * | |
| 84 | + * @param nThreads the number of threads in the pool | |
| 85 | + * @return the newly created thread pool | |
| 86 | + * @throws IllegalArgumentException if {@code nThreads <= 0} | |
| 87 | + */ | |
| 88 | + public static ExecutorService newFixedThreadPool(int nThreads) { | |
| 89 | + return new ThreadPoolExecutor(nThreads, nThreads, | |
| 90 | + 0L, TimeUnit.MILLISECONDS, | |
| 91 | + new LinkedBlockingQueue<Runnable>()); | |
| 92 | + } | |
| 93 | + | |
| 94 | + /** | |
| 95 | + * Creates a thread pool that reuses a fixed number of threads | |
| 96 | + * operating off a shared unbounded queue, using the provided | |
| 97 | + * ThreadFactory to create new threads when needed. At any point, | |
| 98 | + * at most <tt>nThreads</tt> threads will be active processing | |
| 99 | + * tasks. If additional tasks are submitted when all threads are | |
| 100 | + * active, they will wait in the queue until a thread is | |
| 101 | + * available. If any thread terminates due to a failure during | |
| 102 | + * execution prior to shutdown, a new one will take its place if | |
| 103 | + * needed to execute subsequent tasks. The threads in the pool will | |
| 104 | + * exist until it is explicitly {@link ExecutorService#shutdown | |
| 105 | + * shutdown}. | |
| 106 | + * | |
| 107 | + * @param nThreads the number of threads in the pool | |
| 108 | + * @param threadFactory the factory to use when creating new threads | |
| 109 | + * @return the newly created thread pool | |
| 110 | + * @throws NullPointerException if threadFactory is null | |
| 111 | + * @throws IllegalArgumentException if {@code nThreads <= 0} | |
| 112 | + */ | |
| 113 | + public static ExecutorService newFixedThreadPool(int nThreads, ThreadFactory threadFactory) { | |
| 114 | + return new ThreadPoolExecutor(nThreads, nThreads, | |
| 115 | + 0L, TimeUnit.MILLISECONDS, | |
| 116 | + new LinkedBlockingQueue<Runnable>(), | |
| 117 | + threadFactory); | |
| 118 | + } | |
| 119 | + | |
| 120 | + /** | |
| 121 | + * Creates an Executor that uses a single worker thread operating | |
| 122 | + * off an unbounded queue. (Note however that if this single | |
| 123 | + * thread terminates due to a failure during execution prior to | |
| 124 | + * shutdown, a new one will take its place if needed to execute | |
| 125 | + * subsequent tasks.) Tasks are guaranteed to execute | |
| 126 | + * sequentially, and no more than one task will be active at any | |
| 127 | + * given time. Unlike the otherwise equivalent | |
| 128 | + * <tt>newFixedThreadPool(1)</tt> the returned executor is | |
| 129 | + * guaranteed not to be reconfigurable to use additional threads. | |
| 130 | + * | |
| 131 | + * @return the newly created single-threaded Executor | |
| 132 | + */ | |
| 133 | + public static ExecutorService newSingleThreadExecutor() { | |
| 134 | + return new FinalizableDelegatedExecutorService | |
| 135 | + (new ThreadPoolExecutor(1, 1, | |
| 136 | + 0L, TimeUnit.MILLISECONDS, | |
| 137 | + new LinkedBlockingQueue<Runnable>())); | |
| 138 | + } | |
| 139 | + | |
| 140 | + /** | |
| 141 | + * Creates an Executor that uses a single worker thread operating | |
| 142 | + * off an unbounded queue, and uses the provided ThreadFactory to | |
| 143 | + * create a new thread when needed. Unlike the otherwise | |
| 144 | + * equivalent <tt>newFixedThreadPool(1, threadFactory)</tt> the | |
| 145 | + * returned executor is guaranteed not to be reconfigurable to use | |
| 146 | + * additional threads. | |
| 147 | + * | |
| 148 | + * @param threadFactory the factory to use when creating new | |
| 149 | + * threads | |
| 150 | + * | |
| 151 | + * @return the newly created single-threaded Executor | |
| 152 | + * @throws NullPointerException if threadFactory is null | |
| 153 | + */ | |
| 154 | + public static ExecutorService newSingleThreadExecutor(ThreadFactory threadFactory) { | |
| 155 | + return new FinalizableDelegatedExecutorService | |
| 156 | + (new ThreadPoolExecutor(1, 1, | |
| 157 | + 0L, TimeUnit.MILLISECONDS, | |
| 158 | + new LinkedBlockingQueue<Runnable>(), | |
| 159 | + threadFactory)); | |
| 160 | + } | |
| 161 | + | |
| 162 | + /** | |
| 163 | + * Creates a thread pool that creates new threads as needed, but | |
| 164 | + * will reuse previously constructed threads when they are | |
| 165 | + * available. These pools will typically improve the performance | |
| 166 | + * of programs that execute many short-lived asynchronous tasks. | |
| 167 | + * Calls to <tt>execute</tt> will reuse previously constructed | |
| 168 | + * threads if available. If no existing thread is available, a new | |
| 169 | + * thread will be created and added to the pool. Threads that have | |
| 170 | + * not been used for sixty seconds are terminated and removed from | |
| 171 | + * the cache. Thus, a pool that remains idle for long enough will | |
| 172 | + * not consume any resources. Note that pools with similar | |
| 173 | + * properties but different details (for example, timeout parameters) | |
| 174 | + * may be created using {@link ThreadPoolExecutor} constructors. | |
| 175 | + * | |
| 176 | + * @return the newly created thread pool | |
| 177 | + */ | |
| 178 | + public static ExecutorService newCachedThreadPool() { | |
| 179 | + return new ThreadPoolExecutor(0, Integer.MAX_VALUE, | |
| 180 | + 60L, TimeUnit.SECONDS, | |
| 181 | + new SynchronousQueue<Runnable>()); | |
| 182 | + } | |
| 183 | + | |
| 184 | + /** | |
| 185 | + * Creates a thread pool that creates new threads as needed, but | |
| 186 | + * will reuse previously constructed threads when they are | |
| 187 | + * available, and uses the provided | |
| 188 | + * ThreadFactory to create new threads when needed. | |
| 189 | + * @param threadFactory the factory to use when creating new threads | |
| 190 | + * @return the newly created thread pool | |
| 191 | + * @throws NullPointerException if threadFactory is null | |
| 192 | + */ | |
| 193 | + public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) { | |
| 194 | + return new ThreadPoolExecutor(0, Integer.MAX_VALUE, | |
| 195 | + 60L, TimeUnit.SECONDS, | |
| 196 | + new SynchronousQueue<Runnable>(), | |
| 197 | + threadFactory); | |
| 198 | + } | |
| 199 | + | |
| 200 | + /** | |
| 201 | + * Creates a single-threaded executor that can schedule commands | |
| 202 | + * to run after a given delay, or to execute periodically. | |
| 203 | + * (Note however that if this single | |
| 204 | + * thread terminates due to a failure during execution prior to | |
| 205 | + * shutdown, a new one will take its place if needed to execute | |
| 206 | + * subsequent tasks.) Tasks are guaranteed to execute | |
| 207 | + * sequentially, and no more than one task will be active at any | |
| 208 | + * given time. Unlike the otherwise equivalent | |
| 209 | + * <tt>newScheduledThreadPool(1)</tt> the returned executor is | |
| 210 | + * guaranteed not to be reconfigurable to use additional threads. | |
| 211 | + * @return the newly created scheduled executor | |
| 212 | + */ | |
| 213 | + public static ScheduledExecutorService newSingleThreadScheduledExecutor() { | |
| 214 | + return new DelegatedScheduledExecutorService | |
| 215 | + (new ScheduledThreadPoolExecutor(1)); | |
| 216 | + } | |
| 217 | + | |
| 218 | + /** | |
| 219 | + * Creates a single-threaded executor that can schedule commands | |
| 220 | + * to run after a given delay, or to execute periodically. (Note | |
| 221 | + * however that if this single thread terminates due to a failure | |
| 222 | + * during execution prior to shutdown, a new one will take its | |
| 223 | + * place if needed to execute subsequent tasks.) Tasks are | |
| 224 | + * guaranteed to execute sequentially, and no more than one task | |
| 225 | + * will be active at any given time. Unlike the otherwise | |
| 226 | + * equivalent <tt>newScheduledThreadPool(1, threadFactory)</tt> | |
| 227 | + * the returned executor is guaranteed not to be reconfigurable to | |
| 228 | + * use additional threads. | |
| 229 | + * @param threadFactory the factory to use when creating new | |
| 230 | + * threads | |
| 231 | + * @return a newly created scheduled executor | |
| 232 | + * @throws NullPointerException if threadFactory is null | |
| 233 | + */ | |
| 234 | + public static ScheduledExecutorService newSingleThreadScheduledExecutor(ThreadFactory threadFactory) { | |
| 235 | + return new DelegatedScheduledExecutorService | |
| 236 | + (new ScheduledThreadPoolExecutor(1, threadFactory)); | |
| 237 | + } | |
| 238 | + | |
| 239 | + /** | |
| 240 | + * Creates a thread pool that can schedule commands to run after a | |
| 241 | + * given delay, or to execute periodically. | |
| 242 | + * @param corePoolSize the number of threads to keep in the pool, | |
| 243 | + * even if they are idle. | |
| 244 | + * @return a newly created scheduled thread pool | |
| 245 | + * @throws IllegalArgumentException if {@code corePoolSize < 0} | |
| 246 | + */ | |
| 247 | + public static ScheduledExecutorService newScheduledThreadPool(int corePoolSize) { | |
| 248 | + return new ScheduledThreadPoolExecutor(corePoolSize); | |
| 249 | + } | |
| 250 | + | |
| 251 | + /** | |
| 252 | + * Creates a thread pool that can schedule commands to run after a | |
| 253 | + * given delay, or to execute periodically. | |
| 254 | + * @param corePoolSize the number of threads to keep in the pool, | |
| 255 | + * even if they are idle. | |
| 256 | + * @param threadFactory the factory to use when the executor | |
| 257 | + * creates a new thread. | |
| 258 | + * @return a newly created scheduled thread pool | |
| 259 | + * @throws IllegalArgumentException if {@code corePoolSize < 0} | |
| 260 | + * @throws NullPointerException if threadFactory is null | |
| 261 | + */ | |
| 262 | + public static ScheduledExecutorService newScheduledThreadPool( | |
| 263 | + int corePoolSize, ThreadFactory threadFactory) { | |
| 264 | + return new ScheduledThreadPoolExecutor(corePoolSize, threadFactory); | |
| 265 | + } | |
| 266 | + | |
| 267 | + | |
| 268 | + /** | |
| 269 | + * Returns an object that delegates all defined {@link | |
| 270 | + * ExecutorService} methods to the given executor, but not any | |
| 271 | + * other methods that might otherwise be accessible using | |
| 272 | + * casts. This provides a way to safely "freeze" configuration and | |
| 273 | + * disallow tuning of a given concrete implementation. | |
| 274 | + * @param executor the underlying implementation | |
| 275 | + * @return an <tt>ExecutorService</tt> instance | |
| 276 | + * @throws NullPointerException if executor null | |
| 277 | + */ | |
| 278 | + public static ExecutorService unconfigurableExecutorService(ExecutorService executor) { | |
| 279 | + if (executor == null) | |
| 280 | + throw new NullPointerException(); | |
| 281 | + return new DelegatedExecutorService(executor); | |
| 282 | + } | |
| 283 | + | |
| 284 | + /** | |
| 285 | + * Returns an object that delegates all defined {@link | |
| 286 | + * ScheduledExecutorService} methods to the given executor, but | |
| 287 | + * not any other methods that might otherwise be accessible using | |
| 288 | + * casts. This provides a way to safely "freeze" configuration and | |
| 289 | + * disallow tuning of a given concrete implementation. | |
| 290 | + * @param executor the underlying implementation | |
| 291 | + * @return a <tt>ScheduledExecutorService</tt> instance | |
| 292 | + * @throws NullPointerException if executor null | |
| 293 | + */ | |
| 294 | + public static ScheduledExecutorService unconfigurableScheduledExecutorService(ScheduledExecutorService executor) { | |
| 295 | + if (executor == null) | |
| 296 | + throw new NullPointerException(); | |
| 297 | + return new DelegatedScheduledExecutorService(executor); | |
| 298 | + } | |
| 299 | + | |
| 300 | + /** | |
| 301 | + * Returns a default thread factory used to create new threads. | |
| 302 | + * This factory creates all new threads used by an Executor in the | |
| 303 | + * same {@link ThreadGroup}. If there is a {@link | |
| 304 | + * java.lang.SecurityManager}, it uses the group of {@link | |
| 305 | + * System#getSecurityManager}, else the group of the thread | |
| 306 | + * invoking this <tt>defaultThreadFactory</tt> method. Each new | |
| 307 | + * thread is created as a non-daemon thread with priority set to | |
| 308 | + * the smaller of <tt>Thread.NORM_PRIORITY</tt> and the maximum | |
| 309 | + * priority permitted in the thread group. New threads have names | |
| 310 | + * accessible via {@link Thread#getName} of | |
| 311 | + * <em>pool-N-thread-M</em>, where <em>N</em> is the sequence | |
| 312 | + * number of this factory, and <em>M</em> is the sequence number | |
| 313 | + * of the thread created by this factory. | |
| 314 | + * @return a thread factory | |
| 315 | + */ | |
| 316 | + public static ThreadFactory defaultThreadFactory() { | |
| 317 | + return new DefaultThreadFactory(); | |
| 318 | + } | |
| 319 | + | |
| 320 | + /** | |
| 321 | + * Returns a thread factory used to create new threads that | |
| 322 | + * have the same permissions as the current thread. | |
| 323 | + * This factory creates threads with the same settings as {@link | |
| 324 | + * Executors#defaultThreadFactory}, additionally setting the | |
| 325 | + * AccessControlContext and contextClassLoader of new threads to | |
| 326 | + * be the same as the thread invoking this | |
| 327 | + * <tt>privilegedThreadFactory</tt> method. A new | |
| 328 | + * <tt>privilegedThreadFactory</tt> can be created within an | |
| 329 | + * {@link AccessController#doPrivileged} action setting the | |
| 330 | + * current thread's access control context to create threads with | |
| 331 | + * the selected permission settings holding within that action. | |
| 332 | + * | |
| 333 | + * <p> Note that while tasks running within such threads will have | |
| 334 | + * the same access control and class loader settings as the | |
| 335 | + * current thread, they need not have the same {@link | |
| 336 | + * java.lang.ThreadLocal} or {@link | |
| 337 | + * java.lang.InheritableThreadLocal} values. If necessary, | |
| 338 | + * particular values of thread locals can be set or reset before | |
| 339 | + * any task runs in {@link ThreadPoolExecutor} subclasses using | |
| 340 | + * {@link ThreadPoolExecutor#beforeExecute}. Also, if it is | |
| 341 | + * necessary to initialize worker threads to have the same | |
| 342 | + * InheritableThreadLocal settings as some other designated | |
| 343 | + * thread, you can create a custom ThreadFactory in which that | |
| 344 | + * thread waits for and services requests to create others that | |
| 345 | + * will inherit its values. | |
| 346 | + * | |
| 347 | + * @return a thread factory | |
| 348 | + * @throws AccessControlException if the current access control | |
| 349 | + * context does not have permission to both get and set context | |
| 350 | + * class loader. | |
| 351 | + */ | |
| 352 | + public static ThreadFactory privilegedThreadFactory() { | |
| 353 | + return new PrivilegedThreadFactory(); | |
| 354 | + } | |
| 355 | + | |
| 356 | + /** | |
| 357 | + * Returns a {@link Callable} object that, when | |
| 358 | + * called, runs the given task and returns the given result. This | |
| 359 | + * can be useful when applying methods requiring a | |
| 360 | + * <tt>Callable</tt> to an otherwise resultless action. | |
| 361 | + * @param task the task to run | |
| 362 | + * @param result the result to return | |
| 363 | + * @return a callable object | |
| 364 | + * @throws NullPointerException if task null | |
| 365 | + */ | |
| 366 | + public static <T> Callable<T> callable(Runnable task, T result) { | |
| 367 | + if (task == null) | |
| 368 | + throw new NullPointerException(); | |
| 369 | + return new RunnableAdapter<T>(task, result); | |
| 370 | + } | |
| 371 | + | |
| 372 | + /** | |
| 373 | + * Returns a {@link Callable} object that, when | |
| 374 | + * called, runs the given task and returns <tt>null</tt>. | |
| 375 | + * @param task the task to run | |
| 376 | + * @return a callable object | |
| 377 | + * @throws NullPointerException if task null | |
| 378 | + */ | |
| 379 | + public static Callable<Object> callable(Runnable task) { | |
| 380 | + if (task == null) | |
| 381 | + throw new NullPointerException(); | |
| 382 | + return new RunnableAdapter<Object>(task, null); | |
| 383 | + } | |
| 384 | + | |
| 385 | + /** | |
| 386 | + * Returns a {@link Callable} object that, when | |
| 387 | + * called, runs the given privileged action and returns its result. | |
| 388 | + * @param action the privileged action to run | |
| 389 | + * @return a callable object | |
| 390 | + * @throws NullPointerException if action null | |
| 391 | + */ | |
| 392 | + public static Callable<Object> callable(final PrivilegedAction<?> action) { | |
| 393 | + if (action == null) | |
| 394 | + throw new NullPointerException(); | |
| 395 | + return new Callable<Object>() { | |
| 396 | + public Object call() { return action.run(); }}; | |
| 397 | + } | |
| 398 | + | |
| 399 | + /** | |
| 400 | + * Returns a {@link Callable} object that, when | |
| 401 | + * called, runs the given privileged exception action and returns | |
| 402 | + * its result. | |
| 403 | + * @param action the privileged exception action to run | |
| 404 | + * @return a callable object | |
| 405 | + * @throws NullPointerException if action null | |
| 406 | + */ | |
| 407 | + public static Callable<Object> callable(final PrivilegedExceptionAction<?> action) { | |
| 408 | + if (action == null) | |
| 409 | + throw new NullPointerException(); | |
| 410 | + return new Callable<Object>() { | |
| 411 | + public Object call() throws Exception { return action.run(); }}; | |
| 412 | + } | |
| 413 | + | |
| 414 | + /** | |
| 415 | + * Returns a {@link Callable} object that will, when | |
| 416 | + * called, execute the given <tt>callable</tt> under the current | |
| 417 | + * access control context. This method should normally be | |
| 418 | + * invoked within an {@link AccessController#doPrivileged} action | |
| 419 | + * to create callables that will, if possible, execute under the | |
| 420 | + * selected permission settings holding within that action; or if | |
| 421 | + * not possible, throw an associated {@link | |
| 422 | + * AccessControlException}. | |
| 423 | + * @param callable the underlying task | |
| 424 | + * @return a callable object | |
| 425 | + * @throws NullPointerException if callable null | |
| 426 | + * | |
| 427 | + */ | |
| 428 | + public static <T> Callable<T> privilegedCallable(Callable<T> callable) { | |
| 429 | + if (callable == null) | |
| 430 | + throw new NullPointerException(); | |
| 431 | + return new PrivilegedCallable<T>(callable); | |
| 432 | + } | |
| 433 | + | |
| 434 | + /** | |
| 435 | + * Returns a {@link Callable} object that will, when | |
| 436 | + * called, execute the given <tt>callable</tt> under the current | |
| 437 | + * access control context, with the current context class loader | |
| 438 | + * as the context class loader. This method should normally be | |
| 439 | + * invoked within an {@link AccessController#doPrivileged} action | |
| 440 | + * to create callables that will, if possible, execute under the | |
| 441 | + * selected permission settings holding within that action; or if | |
| 442 | + * not possible, throw an associated {@link | |
| 443 | + * AccessControlException}. | |
| 444 | + * @param callable the underlying task | |
| 445 | + * | |
| 446 | + * @return a callable object | |
| 447 | + * @throws NullPointerException if callable null | |
| 448 | + * @throws AccessControlException if the current access control | |
| 449 | + * context does not have permission to both set and get context | |
| 450 | + * class loader. | |
| 451 | + */ | |
| 452 | + public static <T> Callable<T> privilegedCallableUsingCurrentClassLoader(Callable<T> callable) { | |
| 453 | + if (callable == null) | |
| 454 | + throw new NullPointerException(); | |
| 455 | + return new PrivilegedCallableUsingCurrentClassLoader<T>(callable); | |
| 456 | + } | |
| 457 | + | |
| 458 | + // Non-public classes supporting the public methods | |
| 459 | + | |
| 460 | + /** | |
| 461 | + * A callable that runs given task and returns given result | |
| 462 | + */ | |
| 463 | + static final class RunnableAdapter<T> implements Callable<T> { | |
| 464 | + final Runnable task; | |
| 465 | + final T result; | |
| 466 | + RunnableAdapter(Runnable task, T result) { | |
| 467 | + this.task = task; | |
| 468 | + this.result = result; | |
| 469 | + } | |
| 470 | + public T call() { | |
| 471 | + task.run(); | |
| 472 | + return result; | |
| 473 | + } | |
| 474 | + } | |
| 475 | + | |
| 476 | + /** | |
| 477 | + * A callable that runs under established access control settings | |
| 478 | + */ | |
| 479 | + static final class PrivilegedCallable<T> implements Callable<T> { | |
| 480 | + private final Callable<T> task; | |
| 481 | + private final AccessControlContext acc; | |
| 482 | + | |
| 483 | + PrivilegedCallable(Callable<T> task) { | |
| 484 | + this.task = task; | |
| 485 | + this.acc = AccessController.getContext(); | |
| 486 | + } | |
| 487 | + | |
| 488 | + public T call() throws Exception { | |
| 489 | + try { | |
| 490 | + return AccessController.doPrivileged( | |
| 491 | + new PrivilegedExceptionAction<T>() { | |
| 492 | + public T run() throws Exception { | |
| 493 | + return task.call(); | |
| 494 | + } | |
| 495 | + }, acc); | |
| 496 | + } catch (PrivilegedActionException e) { | |
| 497 | + throw e.getException(); | |
| 498 | + } | |
| 499 | + } | |
| 500 | + } | |
| 501 | + | |
| 502 | + /** | |
| 503 | + * A callable that runs under established access control settings and | |
| 504 | + * current ClassLoader | |
| 505 | + */ | |
| 506 | + static final class PrivilegedCallableUsingCurrentClassLoader<T> implements Callable<T> { | |
| 507 | + private final Callable<T> task; | |
| 508 | + private final AccessControlContext acc; | |
| 509 | + private final ClassLoader ccl; | |
| 510 | + | |
| 511 | + PrivilegedCallableUsingCurrentClassLoader(Callable<T> task) { | |
| 512 | + SecurityManager sm = System.getSecurityManager(); | |
| 513 | + if (sm != null) { | |
| 514 | + // Calls to getContextClassLoader from this class | |
| 515 | + // never trigger a security check, but we check | |
| 516 | + // whether our callers have this permission anyways. | |
| 517 | + sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); | |
| 518 | + | |
| 519 | + // Whether setContextClassLoader turns out to be necessary | |
| 520 | + // or not, we fail fast if permission is not available. | |
| 521 | + sm.checkPermission(new RuntimePermission("setContextClassLoader")); | |
| 522 | + } | |
| 523 | + this.task = task; | |
| 524 | + this.acc = AccessController.getContext(); | |
| 525 | + this.ccl = Thread.currentThread().getContextClassLoader(); | |
| 526 | + } | |
| 527 | + | |
| 528 | + public T call() throws Exception { | |
| 529 | + try { | |
| 530 | + return AccessController.doPrivileged( | |
| 531 | + new PrivilegedExceptionAction<T>() { | |
| 532 | + public T run() throws Exception { | |
| 533 | + ClassLoader savedcl = null; | |
| 534 | + Thread t = Thread.currentThread(); | |
| 535 | + try { | |
| 536 | + ClassLoader cl = t.getContextClassLoader(); | |
| 537 | + if (ccl != cl) { | |
| 538 | + t.setContextClassLoader(ccl); | |
| 539 | + savedcl = cl; | |
| 540 | + } | |
| 541 | + return task.call(); | |
| 542 | + } finally { | |
| 543 | + if (savedcl != null) | |
| 544 | + t.setContextClassLoader(savedcl); | |
| 545 | + } | |
| 546 | + } | |
| 547 | + }, acc); | |
| 548 | + } catch (PrivilegedActionException e) { | |
| 549 | + throw e.getException(); | |
| 550 | + } | |
| 551 | + } | |
| 552 | + } | |
| 553 | + | |
| 554 | + /** | |
| 555 | + * The default thread factory | |
| 556 | + */ | |
| 557 | + static class DefaultThreadFactory implements ThreadFactory { | |
| 558 | + private static final AtomicInteger poolNumber = new AtomicInteger(1); | |
| 559 | + private final ThreadGroup group; | |
| 560 | + private final AtomicInteger threadNumber = new AtomicInteger(1); | |
| 561 | + private final String namePrefix; | |
| 562 | + | |
| 563 | + DefaultThreadFactory() { | |
| 564 | + SecurityManager s = System.getSecurityManager(); | |
| 565 | + group = (s != null) ? s.getThreadGroup() : | |
| 566 | + Thread.currentThread().getThreadGroup(); | |
| 567 | + namePrefix = "pool-" + | |
| 568 | + poolNumber.getAndIncrement() + | |
| 569 | + "-thread-"; | |
| 570 | + } | |
| 571 | + | |
| 572 | + public Thread newThread(Runnable r) { | |
| 573 | + Thread t = new Thread(group, r, | |
| 574 | + namePrefix + threadNumber.getAndIncrement(), | |
| 575 | + 0); | |
| 576 | + if (t.isDaemon()) | |
| 577 | + t.setDaemon(false); | |
| 578 | + if (t.getPriority() != Thread.NORM_PRIORITY) | |
| 579 | + t.setPriority(Thread.NORM_PRIORITY); | |
| 580 | + return t; | |
| 581 | + } | |
| 582 | + } | |
| 583 | + | |
| 584 | + /** | |
| 585 | + * Thread factory capturing access control context and class loader | |
| 586 | + */ | |
| 587 | + static class PrivilegedThreadFactory extends DefaultThreadFactory { | |
| 588 | + private final AccessControlContext acc; | |
| 589 | + private final ClassLoader ccl; | |
| 590 | + | |
| 591 | + PrivilegedThreadFactory() { | |
| 592 | + super(); | |
| 593 | + SecurityManager sm = System.getSecurityManager(); | |
| 594 | + if (sm != null) { | |
| 595 | + // Calls to getContextClassLoader from this class | |
| 596 | + // never trigger a security check, but we check | |
| 597 | + // whether our callers have this permission anyways. | |
| 598 | + sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION); | |
| 599 | + | |
| 600 | + // Fail fast | |
| 601 | + sm.checkPermission(new RuntimePermission("setContextClassLoader")); | |
| 602 | + } | |
| 603 | + this.acc = AccessController.getContext(); | |
| 604 | + this.ccl = Thread.currentThread().getContextClassLoader(); | |
| 605 | + } | |
| 606 | + | |
| 607 | + public Thread newThread(final Runnable r) { | |
| 608 | + return super.newThread(new Runnable() { | |
| 609 | + public void run() { | |
| 610 | + AccessController.doPrivileged(new PrivilegedAction<Void>() { | |
| 611 | + public Void run() { | |
| 612 | + Thread.currentThread().setContextClassLoader(ccl); | |
| 613 | + r.run(); | |
| 614 | + return null; | |
| 615 | + } | |
| 616 | + }, acc); | |
| 617 | + } | |
| 618 | + }); | |
| 619 | + } | |
| 620 | + } | |
| 621 | + | |
| 622 | + /** | |
| 623 | + * A wrapper class that exposes only the ExecutorService methods | |
| 624 | + * of an ExecutorService implementation. | |
| 625 | + */ | |
| 626 | + static class DelegatedExecutorService extends AbstractExecutorService { | |
| 627 | + private final ExecutorService e; | |
| 628 | + DelegatedExecutorService(ExecutorService executor) { e = executor; } | |
| 629 | + public void execute(Runnable command) { e.execute(command); } | |
| 630 | + public void shutdown() { e.shutdown(); } | |
| 631 | + public List<Runnable> shutdownNow() { return e.shutdownNow(); } | |
| 632 | + public boolean isShutdown() { return e.isShutdown(); } | |
| 633 | + public boolean isTerminated() { return e.isTerminated(); } | |
| 634 | + public boolean awaitTermination(long timeout, TimeUnit unit) | |
| 635 | + throws InterruptedException { | |
| 636 | + return e.awaitTermination(timeout, unit); | |
| 637 | + } | |
| 638 | + public Future<?> submit(Runnable task) { | |
| 639 | + return e.submit(task); | |
| 640 | + } | |
| 641 | + public <T> Future<T> submit(Callable<T> task) { | |
| 642 | + return e.submit(task); | |
| 643 | + } | |
| 644 | + public <T> Future<T> submit(Runnable task, T result) { | |
| 645 | + return e.submit(task, result); | |
| 646 | + } | |
| 647 | + public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) | |
| 648 | + throws InterruptedException { | |
| 649 | + return e.invokeAll(tasks); | |
| 650 | + } | |
| 651 | + public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, | |
| 652 | + long timeout, TimeUnit unit) | |
| 653 | + throws InterruptedException { | |
| 654 | + return e.invokeAll(tasks, timeout, unit); | |
| 655 | + } | |
| 656 | + public <T> T invokeAny(Collection<? extends Callable<T>> tasks) | |
| 657 | + throws InterruptedException, ExecutionException { | |
| 658 | + return e.invokeAny(tasks); | |
| 659 | + } | |
| 660 | + public <T> T invokeAny(Collection<? extends Callable<T>> tasks, | |
| 661 | + long timeout, TimeUnit unit) | |
| 662 | + throws InterruptedException, ExecutionException, TimeoutException { | |
| 663 | + return e.invokeAny(tasks, timeout, unit); | |
| 664 | + } | |
| 665 | + } | |
| 666 | + | |
| 667 | + static class FinalizableDelegatedExecutorService | |
| 668 | + extends DelegatedExecutorService { | |
| 669 | + FinalizableDelegatedExecutorService(ExecutorService executor) { | |
| 670 | + super(executor); | |
| 671 | + } | |
| 672 | + protected void finalize() { | |
| 673 | + super.shutdown(); | |
| 674 | + } | |
| 675 | + } | |
| 676 | + | |
| 677 | + /** | |
| 678 | + * A wrapper class that exposes only the ScheduledExecutorService | |
| 679 | + * methods of a ScheduledExecutorService implementation. | |
| 680 | + */ | |
| 681 | + static class DelegatedScheduledExecutorService | |
| 682 | + extends DelegatedExecutorService | |
| 683 | + implements ScheduledExecutorService { | |
| 684 | + private final ScheduledExecutorService e; | |
| 685 | + DelegatedScheduledExecutorService(ScheduledExecutorService executor) { | |
| 686 | + super(executor); | |
| 687 | + e = executor; | |
| 688 | + } | |
| 689 | + public ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit) { | |
| 690 | + return e.schedule(command, delay, unit); | |
| 691 | + } | |
| 692 | + public <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit) { | |
| 693 | + return e.schedule(callable, delay, unit); | |
| 694 | + } | |
| 695 | + public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit) { | |
| 696 | + return e.scheduleAtFixedRate(command, initialDelay, period, unit); | |
| 697 | + } | |
| 698 | + public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit) { | |
| 699 | + return e.scheduleWithFixedDelay(command, initialDelay, delay, unit); | |
| 700 | + } | |
| 701 | + } | |
| 702 | + | |
| 703 | + | |
| 704 | + /** Cannot instantiate. */ | |
| 705 | + private Executors() {} | |
| 706 | +} | |